Yoshiaki Takanashi

A case of lymphomatoid granulomatosis/angiocentric immunoproliferative lesion with long clinical course and diffuse brain involvement

Lymphomatoid granulomatosis (LYG)/angiocentric immunoproliferative lesions (AIL) consist of angiocentric and angiodestructive lymphoreticular proliferation predominantly involving the lungs and other extranodal sites, such as the central nervous system (CNS). This clinical entity is considered as a B cell process related to Epstein-Barr virus (EBV) infection and EBV positive diffuse large B-cell lymphoma. The CNS is involved in 20% of cases of LYG, but initial involvement is rare. In cases without pulmonary symptoms, diagnosis may be difficult. We report a rare case involving initial progression of CNS symptoms followed by a pulmonary abnormality.A 14-year-old girl suffered from high fever, ataxic gait and paraparesis. MRI revealed diffuse T2 high signals with multiple gadolinium enhancements in the cerebellum, brain stem and cerebral white matter. Her symptoms briefly improved after steroid therapy, but ataxia gradually progressed. Dyspnea due to pulmonary interstitial involvement appeared when she was 18 years old. Steroid therapy proved effective for respiratory symptoms. At 20 years old she suffered from disseminated intravascular coagulopathy (DIC) and hemophagocytic syndrome (HPS) with respiratory symptoms and repeated seizures. Her symptoms improved after the administration of cyclophosphamide. Mild hemiparesis and gait disturbance appeared when she was 22 years old. MRI revealed new lesions at the basal ganglia and subcortical white matter, brain atrophy and diffuse T2 high intensity of cerebral white matter. Cyclophosphamide was effective and there has been no recurrence of symptoms in the last 5 years. We reviewed the non-tumorous LYG/AIL involving the CNS, and discussed the clinical features, MRI imaging and diagnosis of the LYG/AIL.

A new method for magnetoencephalography: a three-dimensional magnetometer-spatial filter system

A novel three-dimensional magnetometer-spatial filter system was developed to study human brain activity with high spatiotemporal resolution. The system combines the high temporal resolution of magnetoencephalography with the high spatial resolution achieved by using three-dimensional magnetometers and spatial filters to measure the direction and intensity of magnetic fields generated during brain activity. Simulation and phantom studies indicate that the system is capable of mapping current sources of magnetic fields with a spatial resolution comparable to that of any other brain functional imaging technique while maintaining millisecond temporal resolution. Application of this system to the human brain resolved magnetoencephalographic responses evoked by motion stimuli on a millisecond scale into responses occurring in visual cortical areas V1, V2/3 and V5. It also revealed signals related to contextual modulation in V1 and V2/3. This system provides a new way of studying the dynamics of human brain function.

Discrepancy between clinical and pathological diagnoses of CBD and PSP

Progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) are often clinically confused with each other. Moreover, the discrepancy between clinical and pathological diagnoses of CBD and PSP are still controversial. We report here two atypical cases of PSP and CBD. A 73–yearold woman was admitted with right hand rigidity, limb kinetic apraxia and cortical sensory loss. Brain atrophy, hypoperfusion and hypometabolism predominantly in the left frontoparietal lobes indicated CBD clinically. Pathological studies revealed neuronal loss and spongy change without ballooned neurons (BN) in the cerebral cortex. Modified Gallyas–Braak (G–B) staining revealed neurofibrillary tangles (NFTs) and tufted astrocytes, indicating pathological diagnosis of PSP. A 75–year–old man admitted with vertical gaze palsy, neck dystonia, parkinsonism and dementia. Atrophy of the frontal lobes and tegmentum of the midbrain and symmetrical frontal hypoperfusion in SPECT indicated PSP. However, neuronal loss and BN in the frontal lobes and clusters of astrocytic plaques indicated CBD pathologically. The G–B staining was useful for differentiating between CBD and PSP, but our atypical cases bring up a new issue about differential diagnosis of CBD and PSP.

Fatigue and recovery of phosphorus metabolites and pH during stimulation of rat skeletal muscle: an evoked electromyography and in vivo31P-nuclear magnetic resonance spectroscopy study

Abstract31P-nuclear magnetic resonance spectroscopy and evoked electromyography were applied to rat skeletal muscle to examine the mechanism of muscle fatigue and the recovery of muscle phosphorus metabolites and pH during fatigue. When the sciatic nerve was electrically stimulated at 1 Hz, the contraction force of the gastrocnemius muscle decreased gradually to 46% of the maximal force, accompanied by a decrease in phosphocreatine (PCr) and a corresponding increase in inorganic phosphate (Pi) and diprotonated inorganic phosphate (H2PO4−). Neither the amplitudes of compound muscle action potentials (CMAP) nor muscle pH changed significantly. At 10-Hz stimulation, contraction force rapidly decreased to 26% of maximal force, accompanied by a decrease in PCr and increases in Pi and H2PO4−. Muscle pH decreased for a few minutes, then gradually recovered during continued stimulation. The amplitude of the CMAP also decreased for a few minutes and then reached steady values. At 100-Hz stimulation, the contraction force decreased to 6% of the maximal force and there was a decrease in the amplitude of the CMAP. However, the changes in the phosphorus metabolites and pH were transient and recovered to the control value during the stimulation. These results indicated that fatigue at 1 and 100-Hz stimulation was mainly caused by the change in phosphorus metabolite concentrations and electrical failure, respectively, and that fatigue at 10-Hz stimulation might have been due to both of the these factors. These results also indicated that electrical failure might have been the cause of the recovery of the phosphorus metabolites and pH during 100-Hz stimulation and of pH during 10-Hz stimulation.

Ratio of Motor Nerve Conduction Velocity to F-Wave Conduction Velocity in Diabetic Neuropathy

OBJECTIVE To investigate the usefulness of a new parameter, the ratio of motor nerve conduction velocity to F-wave conduction velocity (M/F ratio), for the differential diagnosis of diabetic neuropathy. RESEARCH DESIGN AND METHODS Nerve conduction studies were conducted in 95 patients with diabetic neuropathy, 44 nondiabetic patients with peripheral neuropathy, and 24 normal control subjects. Nondiabetic patients with neuropathy were grouped by clinical diagnosis as follows: segmental demyelination (n = 15), axonal neuropathy (n = 11), alcoholic polyneuropathy (n = 4), and other polyneuropathy (n = 14). Motor nerve conduction velocity (MCV) of post-tibial nerves, sensory nerve conduction velocity (SCV) of sural nerves, and F-wave conduction velocity (FWCV) of post-tibial nerves were measured by standardized techniques. The M/F ratio was calculated from these measurements. RESULTS The MCV and SCV of diabetic patients were significantly slower and the M/F ratio was significantly lower than those of normal subjects: MCV, 43.7 ± 5.4 vs. 47.1 ± 2.9 m/s, P < 0.001; SCV, 44.7 ±11.1 vs. 48.3 ± 5.7 m/s, P < 0.05; M/F ratio, 0.84 ± 0.09 vs. 0.90 ± 0.06, P < 0.001. The FWCV of nondiabetic patients with neuropathy was significantly slower (40.0 ± 6.3 vs. 48.3 ± 4.0 m/s, P < 0.001) and the M/F ratio was significantly higher (1.04 ± 0.12, P < 0.001) than that of normal subjects, respectively. Although MCV, SCV, and FWCV were correlated with age in normal control subjects, the M/F ratio was independent of age in the diabetic as well as the nondiabetic patients with neuropathy. CONCLUSIONS Results suggest that the M/F ratio, which is influenced by the neuronal damages in the distal segment of peripheral nerves, is useful in the differential diagnosis of diabetic neuropathy.

A 129-channel Vector Neuromagnetic Imaging System

We developed a 129-channel vector neuromagnetic imaging system detecting magnetic fields as a vector value. It is expected that further information can be obtained from vector neuromagnetic field than a conventional system. An axial vector first-order gradiometer was developed as a detection coil, which consists of three first-order differential coils wound on the surface of the same bobbin. These three coils are perpendicular to each other. In addition to a radial component of magnetic fields, two tangential components can be calculated from the measured field at each measuring point. The measuring area with a diameter of nearly 20 cm has 43 measuring points. The DC-SQUID which we developed, adopted a double-washer superconducting ring and employed week link Josephson junctions instead of the conventional tunnel junction. Therefore magnetic flux penetrating the SQUID ring is canceled. In addition, the feedback coil is directly connected with the input coil magnetically so that the current in the detection coil can be canceled by the feedback flux. Therefore a crosstalk between adjacent detection coils is negligible. The read-out electronics is based on the Direct Offset Integration Technique. The system noise in a magnetically shielded room is less than 10fT/Hz1/2 above 10Hz. We confirmed that this system could measure various evoked responses. In this report the features of this system and an application will be shown.

Clinical application of magnetoencephalography in a patient with corticobasal degeneration.

Previous neuroimaging studies in corticobasal degeneration (CBD), such as MRI and positron emission tomography, showed lateralized cortical atrophy and a decrease in cortical oxygen metabolism, respectively. The advantage of magnetoencephalography in the research of the auditory system is that activity of both hemispheres can be detected separately. Auditory‐evoked magnetic fields (AEFs) were then applied to a patient with corticobasal degeneration. The strength of N1 OOm equivalent current dipoles (ECD) in left hemisphere was extremely smaller (20 nAm) than that in right hemisphere (48 nAm). This results implies that CBD patient might have a decrease in the number of neurons in the primary auditory cortex. This study suggests that AEF measurement is one of the most powerful tools for detecting latent impairment of auditory function in patients with corticobasal degeneration.

Moving mesh method for reconstructing some spread sources in the brain.

The purpose of this paper is to propose a new algorithm for the analysis of biomagnetic field data obtained from magnetoencephalography (MEG) measurements. This new method overcomes two major problems faced by the current method of data analysis. The first problem is the need to determine the number of sites of brain activity before calculations can be performed. The second problem is inability of the analysis to provide any information regarding the volume of the brain activity. The new data analysis method, called the Moving Mesh Method (MMM), is capable of analyzing MEG data without the need to determine the number of sources beforehand. In addition, the MMM determines the location of brain activity as a three dimensional volume, instead of as a point source of activity. The MMM uses an iterative method of calculating the position of the sources to achieve greater accuracy, and a regularized g-inverse matrix to stabilize its solution. The feasibility of the MMM was examined by two methods. First, a computer simulation was used to confirm the MMMs capability to analyzing MEG data. In the second experiment, the MMM was applied to analyze somatosensory evoked fields obtained using a new imaging system (Shimadzu Biomagnetic Imaging System, Model-100). From the interpretation of the results, we have concluded that the MMM is a feasible method of biomagnetic data analysis.

Scalp topography of SEP late components in patients with supra-tentorial lesions

SummarySomatosensory evoked potentials (SEP) to simultaneous bilateral median nerve stimulation were recorded in 7 patients with unilateral brain lesions, 8 patients with degenerative dementia, and 5 normal volunteers. Right-left amplitude difference was compared from serial topographic images and the amplitude was compared at homologous electrodes. In patients with unilateral lesions, the amplitude from the frontopolar, frontal, anterior-temporal, and/or occipital electrodes was smaller on the affected side at 240 and 360 msec, regardless of whether the subjects showed sensory deficit or not. No significant laterality was seen in the primary sensorimotor areas. Distribution obtained from the patients with degenerative dementia was quite symmetrical. A significant right-left amplitude difference was seen at the anterior temporal site at 180 and 240 msec in normal controls, although an almost symmetrical distribution was obtained on the topographic images. The late components of SEP are not associated with the primary somatosensory function, but possibly with other cortical pathways.

Visualization of Tonotopy of Auditory Cortex Using a Newly Developed 129 Channel Vector Magnetoencephalography

The existence of the human tonotopic organization has been revealed using the neuromagnetic measurement. These early studies on the tonotopic organization in the human were performed by measuring sequentially at many sites using the magnetoencephalography (MEG) with a few channels 1, 2, 3, so these studies needed a vast effort and time to fulfill a study. This meant that we could not use mangentoencephalography (MEG) to investigate the auditory function of patients in clinical setting. Now, many MEG systems, which are commercially available, consist of multi-channel first-order axial gradometers or planar gradiometers. These have some advantages; specially, axial gradiometer is sensitive to the radial component of magnetic fields, and planar gradiometer is favorable to obtain their tangential component. Even using these two systems, however, we could not obtain three dimensional components about magnetic fields. Consequently, we have developed a new 129 channel vector magnetometer system5).